Introduction of widely used antibiotic (florfenicol, enrofloxacin or doxycycline) with the least adverse effect on growth, survival and hematology indices of rainbow trout fingerlings (Oncorhynchus mykiss)
Subject Areas : New Technologies in Aquaculture Development
Keywords: Rainbow trout, Enrofloxacin, Hematological parameters, Doxycycline, Keywords: Florfenicol, Growth and survival indices,
Abstract :
The present study was carried out with aim of the investigating the effects of florfenicol, enrofloxacin, and doxycycline antibiotics on growth and survival indices, and hematology of rainbow trout fingerlings. For this purpose, 720 rainbow trout fingerlings with an average weight of 27.5±2.5 g were fed in 4 treatments including, treatment 1: control, treatment 2: diet with florfenicol antibiotic, treatment 3: diet with enrofloxacin and treatment 4: diet with doxycycline for 40 days. At the end of the test period, the indices of Weight Total (WT), Specific Growth Rate (SGR), Daily Growth Rate (DGR), Feed Efficiency (FER), Feed Conversion Ratio (FCR) and Survival Percentage (SP) were calculated. Also, hematological parameters (WBC, RBC, Hb, Htc %, MCV, MCH, MCHC, lymphocyte, monocyte, neutrophil and eosinophil) were measured. Based on the obtained results, growth and survival indices were affected by florfenicol, enrofloxacin and doxycycline antibiotics and decreased (p<0.05). So that the final weight, specific growth rate, daily growth coefficient, feed efficiency, feed conversion coefficient and survival percentage of control group fish had significant differences compared to other experimental treatments (p<0.05). The reduction of these indices in fish fed with florfenicel was more than that of fish fed with enrofloxacin and doxycycline antibiotics (p<0.05). Among the hematological parameters, the number of white blood cells (WBC) and lymphocyte increased under the influence of antibiotics (p<0.05). Comparing the indices of the number of RBC, Hb, %Htc, MCV, MCH, MCHC, monocyte, neutrophil and eosinophil differences no significance was observed between treatments (p<0.05). Finally, it was concluded that the use of antibiotics has adverse effects on growth, survival and hematology indicators of rainbow trout. But in the meantime, florfenicel had the most and enrofloxacin the least negative effect on these indicators. According to the results obtained from this study, the use of enrofloxacin and doxycycline is recommended when the disease occurs and the antibiotic is prescribed by the veterinarian, compared to the antibiotic florfenicol.
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